Friction lock for screw threads



9 R. ENSINGER ETAL FRICTION LOCK FQR SCREW THREADS Filed. April 8, 19440mg F IN VENTOR.

Patented Sept. 11, 1945 FRICTION LOCK FOR SCREW THREADS Ray Ensinger andJames H. Foote, Detroit, Mich., assignors to George M. Holley and EarlHolley Application April 8, 1944,- Serial No. 530,210

2 Claims.

The object of this invention is to provide means for looking a threadedstud into a comparatively soft metallic casting.

It has heretofore been common practice to make a nut with a fiber insetspun into place, both nut and fiber being threaded on a bolt. Whenapplying the same method to driving a stud into a casing, a differentmethod of making the locking device has to be invented, because it is nolonger possible to spin the casting over so as to engage the fiberinsert.

In forcing the stud into the fiber insert, which is the preferredmethods or in running an undesized tap into the fiber, the fiber must beHeld from rotating and also must be clamped tightly against endmovement.

Hence, the object of this invention is to provide an inexpensive meansfor holding a fiber washer against rotation and also against end thrust.

Figure I shows the parts ready for assembly.

Figure II shows the locating ring.

Figure III hows the fiber washer.

Figure IV shows in cross-sectional elevation the fiber ring locked inplace.

Figure V shows the plan view looking up on Figure II.

In the figures: I is the casting; II is fiber washer; I2 is a steellocking ring shaped in cross section like the letter L. The ring I2 hasa corner I 3 formed between the upper leg which makes an acute anglewith the cylindrical extension I6, which forms the other leg of the L.

In Figure I the method of assembling is illustrated.

A punch I 4 has a short extension I5, which engages with and forms apilot for the inside of the cylindrical extension I6 of the steel ring I2. The drilled hole in the casting has a cylindrical portion II, whichis a little larger than the diameter of the outside diameter of thefiber washer II. A portion I8 of the bore in the casting I 0 has alarger diameter than the bore l1 so that a shoulder I9 is formed betweenthe bores I1 and I8, The punch I4 when driven home presses the corner I3of the steel ring I2 into the shoulder I9 between the two bores I1 andI8 in the casting. The outside diameter of the punch is a little lessthan the diameter of the bore I8. An axial load on the corner I3 of thewasher I2 causes a lateral force to be exerted by the periphery of thewasher which is thus forced into the casting, which may be aluminum orany other casting softer than the material of the steel ring. Theserrations on the lateral and axial legs of the L of the ring I2 shownin Figure revent the fiber ring from rotating. Finally the fiber istapped with an undersized tap so that the fiber will grip the bolt orstud tightly. The serrations on the outside diameter of the ring I2which engage with the opening Hi just above the shoulder I9 prevent thering I2 being pushed during the threading operation.

Operation The fiber washer II is placed in the cylindrical portion II.The steel washer I2 is placed above the fiber washer and is guided bythe cylindrical bore. The punch I4 then descends and is guided into thebore I8. The pilot I5 on the end of the punch enters the inside of thering I2 and the shoulder of the punch engages with the corner I 3 of thering I2. The pilot I5 on the end of the punch I4 being slightly smallerthan the inside diameter of the cylindrical portion I6 of the steel ringI2, the punch I4 guides the ring into place. The steel ring I2 has aportion which is conical and when-pressure is applied to the upper edgeI3 it becomes flat and therefore spreads laterally. The inside diameterI6 cannot be reduced as it is supported by the pilot I5. As a result,the outer edge of the fiat disc thus formed is forced laterally into thecasting at a plane just above the shoulder I9, into the metal matrix.

At the same time, the lower edge of the ring I2 is pushed into the fiberWasher I I. The outer lateral edge of the steel ring I2 is serrated andthe lower edge of the cylindrical portion I6 of ring I2 is alsoserrated. By these means, when these two metal edges of the ring I2 areforced, one down into the fiber, and the other, laterally into thecasting, the fiber is thus locked in place and cannot rotate nor can itbe pushed out.

Subsequently a thread is formed on the fiber by means of an undersizedtap or the bolt itself when forced up from the bottom of the openingwill form a thread in the fiber.

The pilot I5 prevents the inner diameter I6 from interfering with thetop of the thread and the locking ring being forced into the wall of theopening in the casting will not be pushed out. The serrations on thelocking ring prevent the fiber disc rotating. Hence, a tight fiberthread is formed as an extension to the thread in the casting I0.

What we claim is:

1. In a casting of relatively soft metal, a fiber bushing, and L shapedlocking ring having an acute angle and serrated edges and made ofrelatively hard metal, the cylindrical portion of the L being embeddedin the fiber, the transverse portion of the L being forced into lockingengagement with the relatively soft metal by the enlargement of theacute angle of the ring.

2. A fiber locking ring embedded in an opening in a relatively softmetal matrix, a relatively hard metal ring having an L shaped crosssection with serrated edges, the serrrated edge of the axial portionsengaging with the fiber washer, and the radial portion engaging with themetal matrix.

RAY ENSINGER. JAMES H. FOOTE.

